Annealing in water vapor as a new method for improvement of silicon thin film properties

Electronic properties of poly-Si thin films fabricated by atmospheric pressure chemical vapor deposition (APCVD) were improved by annealing in H2O or D2O vapors. Hall mobility was improved from 4.45 cm−2/V s to 25.1 cm−2/V s after 1 h D2O vapor treatment at 300 °C, i.e., nearly the same value as after optimized plasma hydrogenation. Unlike the hydrogen plasma treatment, annealing did not introduce disorder into the material, judged by the width of Raman LO-TO band. Water vapor treatment is a novel approach to improvement of thin films properties, with potentially low cost suitable for mass production of solar cells, but its mechanism is not yet clear.